1. Field of the Invention
This invention relates generally to improved apparatus and method for packaging strand material. More particularly, this invention relates to an improved traversing or spiral mechanism for traversing strand material such as glass strand being wound on a rotating support.
2. Prior Disclosures
Continuous glass fibers are commercially produced by exiting a multiplicity of molten streams from a feeder and applying sufficient pulling force to the streams to attenuate them into fine filaments. A number of filaments are converged to form a strand which is wound onto a package on a rotating support.
In the winding of the glass strands onto the rotating support, the speeds are such that it is not generally possible to precision wind the package with a precise control of the lay down of the strand on the package. The speeds of the strand may be on the order of up to about 5,000 to 10,000 yards per minute (about 4500-9000 m/min). In order to overcome the difficulty with precision winding, it has been the practice to use a traversing mechanism that throws the strand back and forth as the rotating package is moved axially below the traversing mechanism. The utilization of some sort of spiral to agitate the strand prior to its winding is necessary in order to be able to easily withdraw the strand from the forming package. If the strands are wound with each winding next to the prior one such as in a spool, it is not possible to unwind the strands after they are dried.
In U.S. Pat. No. 2,391,870 to Beach, there is disclosed a traversing mechanism comprising two wires in a generally spiral pattern around a central shaft. This device while successful in traversing the strands so that the packages may be unwound does cause some undesirable properties in the fiberglass strand produced. The traversing mechanism of Beach apparently causes the strand to be flat making the product less desirable for uses such as chopping of the strand for resin reinforcement. Further, the spiral such as in Beach is considered to cause breakouts during winding. The traversing mechanism of Beach is not desirable for use as a traversing mechanism for the winding of several strands which have been split from a common bushing and are wound on the same package. The breakouts of the Beach traversing mechanism usually are caused by wear on the shaft of the mechanism by the glass strand hitting against it which leads to abrasion of the strand by the worn area and eventual strand breaking. This necessitates the replacement at relatively short intervals of traversing mechanisms such as in Beach.
In order to overcome the difficulties of the traversing mechanism such as in Beach, it has been proposed that traversing devices of several wires could be utilized such as in U.S. Pat. No. 3,784,121 to Arno et al and in U.S. Pat. No. 3,356,304 to Genson. However, these traverses with a multiplicity of wires are complicated to form as many wires of different design must be formed and then properly located on the traversing device. Therefore, there remains the need for a traversing device that would result in a product of improved quality for chopping, with better resin wetting properties, further there is a need for a device that would result in fewer breakouts of strands during winding. There is a need for a traversing device that would wind split strands so as to result in the ability to unwind better from a forming package and not be joined together by the action of the spiral during winding. Further, there is a need for a traversing mechanism of longer life of simple design and low cost.